int main() {
	//拷贝
	const int a = 10;
	int b = a;					//OK

	//指针拷贝
	const int* const pa = &a;
	/*
	int* p1 = pa;				//ERROR	cannot convert from 'const int *const ' to 'int *'
	int* const p2 = pa;			//ERROR	cannot convert from 'const int *const ' to 'int *'
	*/

	const int* p3 = pa;			//OK

	/*
	int* p4 = &a;				//ERROR cannot convert from 'const int *' to 'int *'
	*/
}